EXPLORING ENVIRONMENTAL DRIVERS OF PHYTOPLANKTON VERTICLE DISTRIBUTION PATTERNS COMPARING IN-SITU CHLA FLUORESCENCE AND HOLOGRAPHIC IMAGING AT FINE-SCALES

Phytoplankton play a vital role in global carbon and nutrient cycling. However, accurately quantifying phytoplankton biomass, productivity, and community composition remains a challenge due to their small size and patchy distribution. A common technique for monitoring phytoplankton biomass is using chlorophyll a (Chla) fluorescence as a proxy. But this method has important limitations - Chla can be influenced by various physiological and environmental parameters, such as dissolved oxygen (DO) and temperature, which can significantly impact primary productivity, and does not provide information on phytoplankton size, shape, or taxonomy. These factors can lead to uncertainties in the relationship between fluorescence and phytoplankton biomass. Advances in in-situ holographic imaging have made it possible to identify and quantify phytoplankton assemblages at cm to meter scales. The integration of multiple monitoring techniques –Chla, DO, temperature, and in-situ holographic imaging–provides a more complete picture of phytoplankton distribution and productivity, as well as the complex interactions between these organisms and their physical-chemical environment. This is especially true for often overlooked benthic primary producers. Preliminary findings indicate notable fluorescence peaks at bottom depths, with holographic particle statistics suggesting this may be related to an abundance of benthic producers, primarily diatoms. Understanding these relationships aids in predicting how phytoplankton respond to climate change and other stressors.

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Primary Presenter: Jess Shearer, University of North Carolina Wilmington (js7102@uncw.edu)

Authors:

Christian Briseño-Avena, University of North Carolina Wilmington  (brisenoavenac@uncw.edu)